Gas turbine engine aerofoil components (i.e. blades or vanes) are traditionally assessed for high cycle fatigue (HCF) by carrying out fatigue tests on sample components. This entails clamping the vane/blade at its end fixings and then mechanically exciting one of the component's modal frequencies. The exciting force can be provided by a mechanical shaker or by a pulsed or constant air jet. Large amplitudes of vibration are generally required in order to produce desired HCF failures.
Organic matrix composite (OMC) aerofoil components are becoming more widely incorporated into gas turbine engines. However, conventional methods of exciting blade/vane vibration modes can be inadequate for such components. In particular, OMCs tend to have high intrinsic damping and hence it can be difficult to excite their vibration modes to high enough amplitudes to cause HCF failure.